Google home cannot access openhab cloud

Tags: #<Tag:0x00007f17368b6bf0>

Since a few days I am not able to execute voice commands with my google home.
I checked the log and I saw the following errors:

2021-02-23 10:35:14.857 [WARN ] [io.openhabcloud.internal.CloudClient] - Jetty request 2872119 failed: HTTP protocol violation: Authentication challenge without WWW-Authenticate header

2021-02-23 10:35:14.858 [WARN ] [io.openhabcloud.internal.CloudClient] - Response Failure: HTTP protocol violation: Authentication challenge without WWW-Authenticate header

I am pretty sure I didn’t change anything.
When I say: OK Google, sync Openhab I receive the message that there was an error and I see the error above in my logs.

I checked my UUID and my secret and saved it in openhabcloud but everything seems ok.

In myopenhab.org it says that my openhab instance is online.
So I am wondering why i cannot use my items with google anymore.

Do you have any hints how I can fix this problem?

openHAB 2 is still working with google assistant.

What version of OH3 are you using

I installed openHAB 3.1.0.M1 but the problem is still there.

no idea? I deleted all things, rules, items and bindings (instead of the cloud binding) so I should have a really clean state.
I removed openhab from my google home services and tried to add it again, but then this error occurs. So currently I am not able to add openhab as a google home service.
I set the loglevel of io.openhabcloud.internal.CloudClient to TRACE but there is not any more output in the logfile.